Application of cone beam computed tomography in bone quality assessment prior to implant placement

The aim of this dissertation was to assess the potential of cone beam computed tomography in bone quality assessment prior to implant placement. The emphasis was on radiographic bone density measurement as one of the most important criteria of bone quality. In chapter 1, the definition of bone quality and its relation with implant treatment success was explained. The application of different modalities in bone density measurement were compared, but the main focus was on MSCT as the gold standard for radiographic bone density measurement and CBCT as the modality under study. Previous efforts on assessing the usefulness of CBCT in bone density measurements were also mentioned. The last part of chapter 1, which is based on a published literature review, briefly introduced the evaluation of bone micro structures, as the second criteria of bone quality. In chapter 2, as the first step of the evaluation of CBCT usefulness in bone quality assessment, the possible correlation between CBCT gray value and MSCT HU were studied. The CBCT machine used for this study was the NewTom 5G (QR, Verona, Italy). Although the actual CBCT gray values deviated from calibrated HU, an excellent correlation was found between these measurements (r=0.96). The correlation of voxel gray values derived from another CBCT scanner (3D Accuitomo 170, J.Morita, Kyoto, Japan) and the calibrated HU was further discussed in chapter 4 and a strong correlation was observed (r=0.89).Therefore, the results showed the potential reliability of the NewTom 5G and 3D Accuitomo 170 in radiographic bone density measurements.